The objective of this proposal is to identify a series of novel small molecule modulators of Hsp90-centered biological networks. Hsp90 is an important oncological target and several compound inhibitors are undergoing clinical trials. A growing interest in exploiting the use of Hsp90 inhibitors for other disease states is emerging including the use of sub-cytotoxic concentrations to increase expression levels of Hsp90 to provide neuroprotection. These inhibitors and others have had an invaluable role in establishing our current knowledge of Hsp90 biology. However, the exact mode of action of Hsp90 inhibitors and their effect on the surrounding cellular networks is still unclear. This problem is not trivial due to the intricate and extensive roles Hsp90 plays in myriad biological processes. Identification of additional pharmacological modulators will have a substantial impact in our ability to modulate Hsp90 pathways. We will exploit the unparalleled knowledge base [unreadable] in yeast genetics and the tractability of the organism to high throughput screening (HTS) to develop an assay capable of identifying chemical modulators, including both antagonists and agonists of Hsp90 pathways. Our genetic-based and multifactorial approach determines growth parameters of a set of yeast strains in the presence of compounds. The growth profiles of these signature strains will aid in identifying compound classes and allow functional linkage with stages of the Hsp90 chaperone cycle and specific subsets of Hsp90 pathways. Solutions to traditional problems with using yeast as a drug-screening platform will be outlined and incorporated in our assay development. The assay we are developing will be in a simple and robust high density 384-well experimental format that will allow screening of a large chemical library matrix such as the Molecular Libraries Small Molecule Repository. [unreadable] [unreadable] [unreadable]